[Bug] Kafka Connect adapter overrides converter schema registry configuration

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Read release policy

- [X] I understand that unsupported versions don't get bug fixes. I will attempt to reproduce the issue on a supported version of Pulsar client and Pulsar broker.

### Version

Linux, Java 17, main

### Minimal reproduce step

Configure a Kafka Connect based IO connector like Debezium and try use it with a Kafka schema registry.
It will appear to work at first because it will write to the mock registry but on restart of the source will fail to read from offsets topic because lookup from schema registry will fail (as mock registry will now be empty).

### What did you expect to see?

That Kafka Connect adapter would transparently pass through properties for schema registry so that url, auth etc can be configured correctly.

### What did you see instead?

`value.converter.schema.registry.url` is forcibly overrriden to `"mock"` making it impossible to use schema registry with Kafka Connect adapter based sources

### Anything else?

_No response_

### Are you willing to submit a PR?

- [X] I'm willing to submit a PR!

Locate the Kafka Connect adapter entry point and trace how value.converter.schema.registry.url and related authentication properties are handled for a Debezium source. Reproduce the mock-registry behavior, then verify that configured schema-registry settings survive a source restart and allow offsets to be read successfully.

Written by the indexing model from the issue text.